The idea of external graphics cards has existed for years, but only in recent years has it become viable. Graphics require a lot of bandwidth, and recent technologies like Thunderbolt 3 and Alienware Graphics Amplifier provide the throughput needed.

AMD's Xconnect technology allows desktop graphics cards to be hooked up to Thunderbolt 3 ports on PCs. One product based on that technology is the US$499 Razer Core, which works with some Razer laptops and an Intel mini-desktop called Skull Canyon.

Dell's Alienware Graphics Amplifier is similar. The latest desktop GPU can be installed in the Amplifier dock, which connects to a specialized port on a PC. The Amplifier uses proprietary technology to talk with PCs. However, it works only with some Alienware PCs, limiting its use to only those loyal to the brand.

But Alienware's Graphics Amplifier has advantages. It will support Nvidia's latest GeForce GTX 1080 and 1070 GPUs, based on the Pascal architecture, something the Thunderbolt 3 external graphics amplifiers can't boast right now, said Frank Azor, general manager of Alienware and XPS PC lines at Dell.

In addition, the internal bandwidth on the Graphics Amplifier cables are dedicated to graphics, Azor said. That's different from Thunderbolt 3, in which bandwidth is broken up among external monitors, storage, and other peripherals daisy-chained to a single port. That division may take away much-needed bandwidth from external graphics cards, Azor said.

The Alienware Graphics Amplifier sells for $199, a drop from the $299 price tag when it was introduced in 2014. The goal at the time was to provide technology where the graphics cards could be easily upgraded without buying a new PC.

Alienware's technology is based on PCI-Express 3.0 technology, and it will be easy to tweak the wires to support PCI-Express 4.0 whenever it is released, Azor said.

It's unclear when PCI-Express 4.0 will be released. However, a server called Zaius being designed by Google and Rackspace, using IBM's Power9 chip, has the PCI-Express 4.0 interconnect.

There's a growing desire for good external graphics cards among users who want to play high-definition games on older laptops, said Dean McCarron, principal analyst at Mercury Research.

Computer owners have experimented with external GPUs since the advent of notebooks. Laptops in older days used to have PCI and ISA slots where external GPUs could be plugged in, but as laptops got smaller, the slots and external GPUs went away.

With Thunderbolt 3 and Alienware's Graphics Amplifier, external graphics technologies can effectively be blended with portability and performance.

It's hard to determine whether Thunderbolt 3 or Alienware technology is superior as each has different hardware technologies and a software stack. But over time, as a common industry standard evolves, proprietary technology will likely go away, McCarron said.

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